Sentence simplification is a process for improving the robustness of spoken language understanding tasks. In conventional systems, simple well-formed sentences may be converted accurately, but the error rate increases as the sentences become more complex. For example, longer, natural, and/or spontaneous utterances often prove difficult to convert and result in inaccurate processing. In some situations, the speaker's intent may be reversed by a negation. Conventional systems depend on word n-grams where n is less than 5; that is, such systems cannot discern intent changes when the changing word is more than five words away in the original sentence.